Demonstration of a state-insensitive, compensated nanofiber trap

We report the experimental realization of an optical trap that localizes single Cs atoms ≃215  nm from the surface of a dielectric nanofiber. By operating at magic wavelengths for pairs of counterpropagating red- and blue-detuned trapping beams, differential scalar light shifts are eliminated, and vector shifts are suppressed by ≈250. We thereby measure an absorption linewidth Γ/2π=5.7±0.1  MHz for the Cs 6S(1/2), F=4→6P(3/2), F'=5 transition, where Γ0/2π=5.2  MHz in free space. An optical depth d≃66 is observed, corresponding to an optical depth per atom d1≃0.08. These advances provide an important capability for the implementation of functional quantum optical networks and precision atomic spectroscopy near dielectric surfaces.

Relationship between auditory thresholds, central spontaneous activity, and hair cell loss after acoustic trauma

Acoustic trauma caused by exposure to a very loud sound increases spontaneous activity in central auditory structures such as the inferior colliculus. This hyperactivity has been suggested as a neural substrate for tinnitus, a phantom hearing sensation. In previous studies we have described a tentative link between the frequency region of hearing impairment and the corresponding tonotopic regions in the inferior colliculus showing hyperactivity. In this study we further investigated the relationship between cochlear compound action potential threshold loss, cochlear outer and inner hair cell loss, and central hyperactivity in inferior colliculus of guinea pigs. Two weeks after a 10-kHz pure tone acoustic trauma, a tight relationship was demonstrated between the frequency region of compound action potential threshold loss and frequency regions in the inferior colliculus showing hyperactivity. Extending the duration of the acoustic trauma from 1 to 2 hours did not result in significant increases in final cochlear threshold loss, but did result in a further increase of spontaneous firing rates in the inferior colliculus. Interestingly, hair cell loss was not present in the frequency regions where elevated cochlear thresholds and central hyperactivity were measured, suggesting that subtle changes in hair cell or primary afferent neural function are sufficient for central hyperactivity to be triggered and maintained.

Three-electron interatomic Coulombic decay from the inner-valence double-vacancy states in NeAr

We have unambiguously identified interatomic Coulombic decay in NeAr from the inner-valence double-vacancy state Ne-Ar(2+)(3s(-2)) to outer-valence triple-vacancy states Ne(+)(2p(-1))-Ar(2+)(3p(-2)) by momentum-resolved electron-ion multicoincidence. This is the first observation of interatomic Coulombic decay where three electrons (3e) participate. The results suggest that this 3e interatomic Coulombic decay is significantly faster than other competing processes like fluorescence decay and charge transfer via curve crossing.

Noise trauma impairs neurogenesis in the rat hippocampus

The hippocampus, a major site of neurogenesis in the adult brain, plays an important role in memory. Based on earlier observations where exposure to high-intensity noise not only caused hearing loss but also impaired memory function, it is conceivably that noise exposure may suppress hippocampal neurogenesis. To evaluate this possibility, nine rats were unilaterally exposed for 2 h to a high-intensity, narrow band of noise centered at 12 kHz at 126 dB SPL. The rats were also screened for noise-induced tinnitus, a potential stressor which may suppress neurogenesis. Five rats developed persistent tinnitus-like behavior while the other four rats showed no signs of tinnitus. Age-matched sham controls showed no signs of hearing loss or tinnitus. The inner ear and hippocampus were evaluated for sensory hair cell loss and neurogenesis 10 weeks post-exposure. All noise exposed rats showed severe loss of sensory hair cells in the noise-exposed ear, but essentially no damage in the unexposed ear. Frontal sections from the hippocampus were immunolabeled for doublecortin to identify neuronal precursor cells, or Ki67 to label proliferating cells. Noise-exposed rats showed a significant reduction of neuronal precursors and fewer dividing cells as compared to sham controls. However, we could not detect any difference between rats with behavioral evidence of tinnitus versus rats without tinnitus. These results show for the first time that high intensity noise exposure not only damages the cochlea but also causes a significant and persistent decrease in hippocampal neurogenesis that may contribute to functional deficits in memory.

Effect of household passive smoking exposure on the risk of ischaemic heart disease in never-smoke female patients in Hong Kong

OBJECTIVE

To investigate the relation between household passive smoking exposure and risk of ischaemic heart disease (IHD) among never-smoke female patients by a retrospective case-control analysis.

METHODS

This study recruited 314 patients with IHD who had never smoked and 319 controls who were admitted for other reasons in the same hospital during the same period. Subjects were interviewed about their exposure to household passive smoking. The dose metrics of passive smoking exposure were evaluated by using "pack years" and "hour years", which indicated the cumulative amount and duration of exposure. The ORs and 95% CIs were computed by unconditional logistic regression, adjusted for other risk factors.

RESULTS

Subjects with passive smoking exposure were associated with higher risk of IHD (OR 1.51, 95% CI 1.01 to 2.27, p = 0.043) when compared to non-exposed subjects. Subjects exposed to an average of > or =1 pack of cigarette per day had an OR of 1.69 (95% CI 1.07 to 2.68, p = 0.025). The OR was 1.52 for those exposed for > or =5 years (95% CI 1.01 to 2.29, p = 0.043) and was 1.82 for those exposed > or =4 h per day (95% CI 1.05 to 3.15, p = 0.032). Similarly, the risk of IHD increased with cumulative exposure duration, with an OR of 1.53 (95% CI 1.01 to 2.32, p = 0.043) at the exposure level > or =5 pack years, and an OR of 1.61 (95% CI 1.03 to 2.52, p = 0.037) at the exposure level > or =20 hour years. There was a significant dose-response association between the exposure measures and risk of IHD (p<0.01 for trend).

CONCLUSION

Our data suggested an increased risk of IHD from passive household smoking in female never-smoke subjects, and demonstrated a dose-response association.

Differential expression of apoptosis-related genes in the cochlea of noise-exposed rats

Exposure to intense noise induces apoptosis in hair cells in the cochlea. To identify the molecular changes associated with noise-induced apoptosis, we used quantitative real-time PCR to evaluate the changes in 84 apoptosis-related genes in cochlear samples from the sensory epithelium and lateral wall. Sprague-Dawley rats exposed to a continuous noise at 115 dB SPL for 2 h. The exposure caused a 40-60 dB threshold shift 4 h post-exposure that decreased to 20-30 dB 7 days post-exposure. These functional changes were associated with apoptotic markers including nuclear condensation and fragmentation and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Immediately after the noise exposure, 12 genes were downregulated, whereas only one gene (Traf4) was upregulated. At 4 h post-exposure, eight genes were upregulated; three (Tnrsf1a, Tnfrsf1b, Tnfrst5) belonged to the Tnfrsf family, three (Bir3, Mcl1 and Prok2) have anti-apoptotic properties and one (Gadd45a) is a target of p53. At 7 days post-exposure, all the upregulated genes returned to pre-noise levels. Interestingly, the normal control cochlea had high constitutive levels of several apoptosis-related genes. These constitutively expressed genes, together with the inducible genes, may participate in the induction of cochlear apoptotic activity.

Quality factor control and lasing characteristics of InAs/InGaAs quantum dots embedded in photonic-crystal nanocavities

We demonstrate lasing action with a high spontaneous emission factor and temperature insensitivity in InAs/InGaAs quantum dots (QD) embedded in photonic crystal nanocavities. A quality factor (Q) of over 10,000 was achieved by suppressing the material absorption by QDs uncoupled to the cavity mode. High Q cavities exhibited ultra low threshold lasing with a spontaneous emission factor of 0.7. Less frequent carrier escape from the QDs, which was primarily favored by high potential barrier energy, enabled low threshold lasing up to 90 K.

Optimized joystick controller

The purpose of the study was to develop an optimized joystick control interface for electric powered wheelchairs and thus provide safe and effective control of electric powered wheelchairs to people with severe physical disabilities. The interface enables clinicians to tune joystick parameters for each individual subject through selecting templates, dead zones, and bias axes. In terms of hand tremor usually associated with people with traumatic brain injury, cerebral palsy, and multiple sclerosis, fuzzy logic rules were applied to suppress erratic hand movements and extract the intended motion from the joystick. Simulation results were presented to show the graphical tuning interface as well as the performance of the fuzzy logic controller.

Salicylate- and quinine-induced tinnitus and effects of memantine

CONCLUSION

Memantine, an antiglutamatergic drug, has been proposed as a treatment for tinnitus.

OBJECTIVES

The purpose of this study was to determine if memantine would prevent salicylate-induced tinnitus. Local field potentials were also recorded from auditory cortex to determine what effect salicylate, memantine, and the combination of both drugs would have on evoked potential amplitudes.

MATERIALS AND METHODS

Schedule induced polydipsia-avoidance conditioning was used to identify the doses of salicylate or quinine that reliably induced tinnitus in rats. Rats were trained to lick for water during quiet intervals and avoid licking during sound intervals.

RESULTS

Rats injected with saline or a low dose of sodium salicylate or quinine failed to develop tinnitus-like behaviors. However, high doses of salicylate (150-300 mg/kg/day) or quinine (100-150 mg/kg/day) greatly reduced licks-in-quiet, behavior consistent with the presence of tinnitus. Licks-in-quiet increased slightly when memantine (1.5 or 3 mg/kg/day) was co-administered with salicylate; however, the effect was not statistically significant or dose-dependent. These results indicate that memantine does not completely suppress salicylate-induced tinnitus. Cortical auditory evoked potential amplitude increased after salicylate treatment; co-administration of memantine failed to block this salicylate-induced increase.

Regulation of secretion of osteoprotegerin in rat dental follicle cells

Tooth eruption requires alveolar bone resorption and formation, both of which appear to be regulated by the dental follicle. Osteoclastogenesis needed for this bone resorption appears to occur as a result of a reduction in the expression of the osteoprotegerin (OPG) gene in the dental follicle at a specific time. This reduction in expression is mediated in vitro in the follicle cells by colony-stimulating factor-1 (CSF-1) and parathyroid hormone-related protein (PTHrP). Using enzyme-linked immunosorbent assays and immunoblotting, this study shows that the reduction in expression of OPG after incubation of the dental follicle cells in either CSF-1 or PTHrP also results in a reduction in its secretion. We also show, by laser capture microdissection, that PTHrP is expressed in vivo in the stellate reticulum such that it could inhibit OPG expression via a paracrine effect on the follicle. Bone formation is enhanced by OPG secretion, and incubation of the follicle cells with bone morphogenetic protein-2 (BMP-2) enhances OPG secretion. Thus, a reduction in secretion of the OPG protein at defined times may promote the osteoclastogenesis and alveolar bone resorption needed for eruption, and enhancement of OPG secretion at other times may promote alveolar bone formation.

Pifithrin-alpha suppresses p53 and protects cochlear and vestibular hair cells from cisplatin-induced apoptosis

Cisplatin, a commonly used antineoplastic agent, destroys the sensory hair cells in the cochlear and vestibular system leading to irreversible hearing loss and balance problems. Cisplatin-induced hair cell damage presumably occurs by apoptosis. Recent studies suggest that p53 may play an important role initiating cisplatin-induced apoptosis in some cell types. To determine if p53 plays a role in cisplatin-mediated hair cell loss, cochlear and utricular organotypic cultures were prepared from postnatal day 3-4 rats and treated with cisplatin or cisplatin plus pifithrin-alpha (PFT), a p53 inhibitor. Control cultures were devoid of p53 immunolabeling, caspase-1 and caspase-3 labeling and p53 protein was absent from Western blots. Cisplatin (1-10 microg/ml) caused a dose-dependent loss of hair cells in cochlear and utricular cultures, up-regulated phospho-p53 serine 15 immunolabeling, increased the expression of phospho-p53 serine 15 in Western blots from 6 to 48 h after the onset of cisplatin-treatment, and increased caspase-1 and caspase-3 labeling in cochlear and vestibular cultures. Addition of PFT (20-100 microM) to cisplatin-treated cochlear and utricular cultures resulted in a dose-dependent increase in hair cell survival; suppressed the expression of p53 in Western blots and eliminated caspase-1 and caspase-3 labeling in cultures. These results suggest that the tumor suppressor protein, p53, plays a critical role in initiating apoptosis in cochlear and vestibular hair cells. Temporary suppression of p53 with PFT provides significant protection against cisplatin-induced hair cell loss and offers the potential for reducing the ototoxic, vestibulotoxic and neurotoxic side effects of cisplatin.

The role of glutathione in carboplatin ototoxicity in the chinchilla

The role of glutathione in carboplatin ototoxicity was investigated in the chinchilla. Chinchillas hearing was tested with both distortion product otoacoustic emissions (DPOAE) and evoked potentials recorded from a chronic electrode in the inferior colliculus (IC). All subjects had an osmotic pump fitted to their right ear and it received buthionine sulfoximine (BSO) at a dose of 15 mM delivered at 5 ml per hour for 14 days. A group (N=4) was given a double dose of carboplatin (25 mg/kg i.p. for 2 days). The pump was implanted three days before the carboplatin dose. The BSO treated ears showed a greater loss in both evoked potential and DPOAE measures, as well as substantially fewer missing hair cells. The results implicate reactive oxygen species (ROS) as a common factor in ototoxic reactions because suppression of glutathione antioxidant leads to greater ototoxic reactions.

A review of the effects of selective inner hair cell lesions on distortion product otoacoustic emissions, cochlear function and auditory evoked potentials

Carboplatin, a second-generation antineoplastic drug, is much less ototoxic than cisplatin in humans and many laboratory animals. However, when a moderate dose of carboplatin is administered to chinchillas, it can selectively destroy inner hair cells (IHCs) and type-I ganglion neurons without damaging the outer hair cells (OHCs). One of the earliest signs of injury from carboplatin is damage to type I, spiral ganglion neurons. Selective destruction of IHCs has no effect on the cochlear microphonic (CM) potential and distortion product otoacoustic emissions (DPOAEs). However, very high doses of carboplatin can destroy both OHCs and IHCs resulting in a decline in CM and DPOAE amplitude. In cases where carboplatin partially destroys the IHCs, the auditory nerve fibers that contact the residual IHCs have normal thresholds and tuning, but their spontaneous and driven discharge rates are reduced. These results suggest that OHCs are responsible for the sharp tuning and exquisite sensitivity of the cochlea. IHC loss leads to a reduction in neural input (i.e., sensory deprivation) to the central auditory system. Surprisingly, although the neural input to the central auditory system is reduced, evoked response amplitudes recorded from the auditory cortex are often enhanced. These results indicate that when the neural input to the central auditory brain is reduced, the central auditory system compensates for the reduced input by increasing its gain.

Epi-inositol regulates expression of the yeast INO1 gene encoding inositol-1-P synthase

Myo-inositol exerts behavioral effects in animal models of psychiatric disorders and is effective in clinical trials in psychiatric patients. Interestingly, epi-inositol exerts behavioral effects similar to myo-inositol, even though epi-inositol is not a substrate for synthesis of phosphatidylinositol. We postulated that the behavioral effects of epi-inositol may be due to its effects on gene expression. Yeast INO1expression was measured in northern blots. INM1 was determined by beta-galactosidase activity in a strain containing the fusion gene INM1-lacZintegrated into the genome. Epi-inositol affects regulation of expression of the INO1 gene (encoding inositol-1-P synthase), even though it cannot support growth of an inositol auxotroph (suggesting that, as in mammalian cells, it is not incorporated into phosphatidylinositol). Like myo-inositol, although to a lesser extent, epi-inositol causes a significant reduction in INO1 expression, and reverses the lithium- or valproate-induced increase in INO1 expression. However, it does not affect regulation of INM1 (encoding inositol monophosphatase), the expression of which is up-regulated by myo-inositol. The observed regulatory effects of epi-inositol on expression of the most highly regulated gene in the inositol biosynthetic pathway may help to explain how this inositol isomer can exert behavioral effects without being incorporated into phosphatidylinositol.

Anatomical, metabolic and genetic aspects of age-related hearing loss in mice

Because of their short lifespan and genetic homogeneity, mice can provide valuable insights into the biological basis of age-related hearing loss. In C57BL/6 mice, hair cell loss begins around 1-2 months of age and progresses rapidly along a base-to-apex gradient, whereas CBA mice show relatively little hair cell loss until late in life. This anatomical difference is reflected in dehydrogenase histochemistry, an indirect measure of aerobic energy metabolism. A small, but significant, decrease in hair cell dehydrogenase staining occurred in CBA mice between 1.5 and 18 months of age. Significantly, dehydrogenase levels in 1.5-month C57 mice were substantially lower than in CBA mice of any age. Thus, deficits in aerobic energy metabolism presage degeneration of the hair cells. The superoxide radical, O2*-, a normal byproduct of cellular metabolism, is potentially toxic and can cause cellular damage if it is not inactivated by superoxide dismutases. Cytosolic copper/zinc superoxide dismutase (SOD1) is highly expressed in the cochlea. Knockout mutant mice with a single (HET) or double deletion (KO) of the Sod1 gene coding for SOD1 showed greater age-related losses than wild-type (WT) mice. KO mice had the worst hearing, WT the best, and HETs were intermediate. KOs exhibited considerably greater hair cell loss than WT mice; however, losses in KOs were only slightly greater than in HETs. KO mice showed significantly greater loss of spiral ganglion cells and nerve fibers than WT mice. These results indicate that SOD1 and O2*- play important roles in age-related hearing loss. Intervention strategies targeting O2*- may reduce age-related hearing loss.

[The effects of the polysaccharides from Dermatocarpon miniatum on oxygen radicals and lipid peroxidation]

OBJECTIVE

To study the effects of Dermatocarpon miniatum (DEM) polysaccharides scavenging oxygen radicals and inhibiting lipid peroxidation.

METHODS

.OH was produced by Fenton reaction and O2-. was produced by the oxidation of pyrogallol. The inhibition to LPO was determined by the colorimetry for testing the relative content of MDA.

RESULTS

DEM polysaccharides could scavenge oxygen radical. The amounts of scavenging 50% (EC50) .OH was 1.72 mg/ml, the EC50 for O2-. was 2.12 mg/ml. DEM polysaccharides could also decrease the content of MDA.

CONCLUSION

DEM polysaccharides has the effects of scavenging oxygen radicals and the inhibition to LPO. Its activities showed positive correlation with the amounts.

Effect of inner and outer hair cell lesions on electrically evoked otoacoustic emissions

When the cochlea is stimulated by a sinusoidal current, the inner ear emits an acoustic signal at the stimulus frequency, termed the electrically evoked otoacoustic emission (EEOAE). Recent studies have found EEOAEs in birds lacking outer hair cells (OHCs), raising the possibility that other types of hair cells, including inner hair cells (IHCs), may generate EEOAEs. To determine the relative contribution of IHCs and OHCs to the generation of the EEOAE, we measured the amplitude of EEOAEs, distortion product otoacoustic emissions (DPOAEs), the cochlear microphonic (CM) and the compound action potential (CAP) in normal chinchillas and chinchillas with IHC lesions or IHC plus OHC lesions induced by carboplatin. Selective IHC loss had little or no effect on CM amplitude and caused a slight reduction in mean DPOAE amplitude. However, IHC loss resulted in a massive reduction in CAP amplitude. Importantly, selective IHC lesions did not reduce EEOAE amplitude, but instead, EEOAE amplitude increased at high frequencies. When both IHCs and OHCs were destroyed, the amplitude of the CM, DPOAE and EEOAE all decreased. The increase in EEOAE amplitude seen with IHC loss may be due to (1) loss of tonic efferent activity to the OHCs, (2) change in the mechanical properties of the cochlea or (3) elimination of EEOAEs produced by IHCs in phase opposition to those from OHCs.

Treatment effects on carbon dioxide retention in patients with obstructive sleep apnea-hypopnea syndrome

OBJECTIVES

This study was designed to examine respiratory control in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), with or without CO(2) retention.

METHODS

We recruited 10 body mass index-matched, apnea-hypopnea index-matched, age-matched, and lung function-matched OSAHS patients, according to their awake PaCO(2). Five patients were hypercapnic (PaCO(2), > or = 45 mm Hg), and five patients were eucapnic. Hypoxic responses (the ratio of the change in minute ventilation [DeltaV(E)] to the change in arterial oxygen saturation [DeltaSaO(2)] and the ratio of the change in mouth occlusion pressure over the first 100 ms of inspiration against an occluded airway [DeltaP(0.1)] to DeltaSaO(2)) and hypercapnic responses (DeltaV(E)/DeltaPCO(2) ratio and DeltaP(0.1)/DeltaPCO(2) ratio) were tested during wakefulness before treatment in all 10 patients, and before and during treatment (at 2, 4, and 6 weeks) with pressure support in the hypercapnic group.

RESULTS

Hypercapnic patients had lower mean (+/- SD) DeltaV(E)/DeltaSaO(2) ratio than eucapnic patients (-0.17 +/- 0.04 vs -0.34 +/- 0.04 L /min/%SaO(2), respectively), lower mean DeltaP(0.1)/DeltaSaO(2) ratio (-0.04 +/- 0.02 vs -0.14 +/- 0.03 cm H(2)O/%SaO(2), respectively), and lower DeltaP(0.1)/DeltaPCO(2) ratio (0.23 +/- 0.1 vs 0.49 +/- 0.1 cm H(2)O/mm Hg, respectively) [p < 0.05]. After receiving noninvasive ventilation treatment, the hypercapnic and hypoxic responses of the hypercapnic patients increased. At 4 to 6 weeks, values for both responses had increased to within the normal range and PaCO(2) had fallen to < 45 mm Hg, while weight was unchanged.

CONCLUSIONS

Depressed chemoresponsiveness plays a role that is independent of obesity in the development of CO(2) retention in some OSAHS patients, and it may be a response to sleep-disordered breathing.